The present invention relates to a polygon mirror for scanning lights such as laser beams.
FIG. 11 shows a conventional polygon mirror, and in particular an octahedron mirror, having a reflecting surface 11 and a shaft-mounting hole 12. Glass or metal is cut to form the polygon mirror.
However, it is difficult to manufacture a large polygon mirror such as a polygon mirror for a processing laser.
In order to solve the above problem, as disclosed in the Japanese Laid-open Publication No. 2-173718 and shown in FIG. 12, a glass plate 14 with a total reflection coating is attached to its peripheral portion of a metal polygonal base 13 via a silicon rubber adhesive agent 15. The base 13 includes a mounting hole 5. The above polygon mirror is large in size and is easily manufactured.
However, since the polygon mirror is manufactured by attaching the glass plate 14 to the base 13, it is impossible to adjust a direction along which a laser beam is reflected by the reflecting surface of the glass plate 14 with respect to the attaching surface of the base 13 after assembly. When a part of the reflecting surface is damaged, it is difficult to repair the part thereof, and then, the polygon mirror should be exchanged for a new one.